The present invention relates to a novel monomer, polymers made from this monomer and a polymer-matrix composite produced therefrom. The present invention also relates to methods of producing the polymer and the polymer-matrix composite.
The field where the present invention finds one of its beneficial applications is in the manufacture of heat-resistant component materials such as those used in jet aircraft. In this and other applications, it is vital that the materials have both sufficient strength and temperature resistance to perform in environments where the materials are exposed to high stresses and temperatures as well as where such stresses, temperatures and other conditions--such as ambient pressure--may vary widely during the material's performance.
With regard to composite materials, it is important that their components, i.e. the polymer(s) and the matrices from which the composites are made, impart sufficient strength to the composite once formed. Such strength is generally a function of the molecular, microscopic and macroscopic character of the components themselves and that of the polymerization and compositing process which bring about the final product.
As regards the polymer itself, several polymers have been developed to yield high strength. One aspect of polymer design is the use of molecularly rigid chemical moities, adjoined by high bond strength, which in turn impart corresponding rigidity and strength to the finished polymer. An example of polymers of this general type are disclosed, for instance, in U.S. Pat. Nos. 4,097,409 to Preston, 4,845,183 to Mueller, et al. and 4,866,155 to Khanna, et al. However, such polymers have not been advantageously designed to yield the optimal characteristics, both in processing of the composite and in the final composite product itself.
In addition to the strength and heat resistance of the polymer itself, it has been found that it is very important to minimize, or even virtually eliminate, interstitial void spaces in the composite product. Such voids may be caused by the physical processing or by the pressure of volatile substances (usually solvent or volatile by-products of polymerization). Thus it is desirable to create both a combination of polymer and reinforcement, and a polymerization-compositing method which most effectively and efficiently minimizes or eliminates solvent and volatile by-products as the composite is formed.
One of the countervailing considerations, however, is that the polymer must maintain sufficient flow characteristics during processing so that it can easily be processed and brought into intimate contact with the reinforcement. Accordingly, it is required that, although solvent be finally removed, that the polymer be able to maintain appropriate flow characteristics throughout the polymerization compositing process.
With regard to the minimization of volatile by-products, it is desirable to create polymer systems which have the advantages of (1) producing relatively small amounts of volatile by-products and (2) being amenable to processing which removes most of the volatiles before they can affect the integrity of the final composite product (i.e. before the final curing step).